Effect of nanosecond pulsed laser parameters on machining characteristics of C/C composites

Carbon fiber reinforced carbon composites (C/C) feature low coefficient of thermal expansion, excellent corrosion resistance, high thermal shock resistance and good wear resistance, which endows them with extensive applications in the aerospace field. However, C/C composites are typical hard-to-machine materials. In conventional machining processes, defects such as fiber pull-out, surface cracks and heat-affected zone (HAZ) are prone to occur, along with low machining efficiency. Laser machining boasts high machining quality, non-contact operation, low thermal input and easy automation. In this paper, a three-dimensional temperature field model is established by using finite element analysis software. Laser power and scanning speed are taken as influencing factors, while temperature rise, micro-groove cutting width, depth and HAZ width are selected as experimental indexes for simulation calculation. A thermal-stress coupling simulation model for laser machining of C/C composites is built. With different laser process parameters as independent variables, the stress and strain of the material are taken as dependent variables to analyze their variation trends. There are numerous factors affecting machining quality during laser machining. It is impossible to fully grasp the variation laws of machining characteristics only by simulation calculation. Therefore, laser machining experiments are carried out in this paper. In this paper, laser machining experiments are conducted to obtain the influence laws of process parameters such as laser power and scanning speed on the micro-groove morphology dimensions and thermal deformation. These experimental results are further compared with the simulation results, which verifies the rationality of the simulation model.